A typical scroll machine has an orbiting scroll member having a spiral wrap on one face thereof, a non-orbiting scroll member having a spiral wrap on one face thereof with said wraps being entermeshed with one another, ad means for causing said orbiting scroll member to orbit about an axis with respect to said non-orbiting scroll member, whereby said wraps will create pockets of progressively decreasing volume from a suction zone to a discharge zone.
It has been discovered that one of the unique features of scroll machines is that excessive high temperature discharge gas conditions (which result from the high pressure ratios caused by many different field-encountered problems) can be solved by providing means to cause a high-side to low-side leak during these conditions.
It is therefore one of the primary objects of the present invention to provide an improved mode of temperature protection which is extremely simple in construction, utilizing a simple temperature responsive valve, and which is easy to install and inspect, and which effectively provides the control desired. The valve of the present invention has been discovered to be particularly good at providing pressure ratio and hence high temperature protection, particularly in motor-compressors where suction gas is used to cool the motor. This is because the valve will create a leak from the high side to the low side at discharge temperatures which are significantly higher than those for which the machine was designed. This leakage of discharge fluid to the suction side of the compressor essentially causes the machine to cease any significant pumping, and the resulting heat build-up within the compressor enclosure and lack of flow of relatively cool suction gas will cause the standard motor protector to trip and shut the machine down. The present invention therefore provides protection from excessive discharge temperatures which could result from (a) loss of working fluid charge, or (b) a blocked condensor fan in a refrigeration system, or (c) a low pressure condition or a blocked suction condition or (d) an excess discharge pressure condition for any reason whatever. All of these undesirable conditions will cause a scroll machine to function at a pressure ratio much greater than that which is designed into the machine in terms of its predetermined fixed volume ratio, and this will in turn cause excessive discharge temperatures.
These and other objects and advantages will become more apparent when viewed in light of the accompanying drawings and following detailed description.